This invention relates to new 3- and/or 4-substituted derivatives of quinic acid and to a process for their production.
Derivatives of quinic acid are widespread in the vegetable world. The chlorogenic acid content of green coffee beans, for example, can represent up to 10% of the dry matter. The term "chlorogenic acid" in fact encompasses a relatively complex mixture of quinic acid derivatives, including caffeoyl, dicaffeoyl, p-coumaroyl, feruloyl and caffeoylferuloyl quinic acids. After roasting, the coffee grains contain an even more complex mixture of compounds of which some are formed by lactones of quinic acids known as quinides or even other isomers formed during the heat treatment. Some of these derivatives show antimicrobial activity, opiate antagonistic activity, anti-inflammatory activity, fungistatic activity, cytostatic activity and inhibiting activity in the biosynthesis of leucotrienes. Applicants have found that some of these compounds show anti-urease activity, their use being the subject of a copending application filed by applicants under the title "An Anti-Urease Cosmetic or Dermatological Composition".
The synthesis of hydroxycinnamoyl quinic acids is described, for example, by E. Haslam et al. in J. Chem. Soc. 1964, 2137-2146. However, the known processes involve a delicate and laborious separation step based on the technique of countercurrent distribution in order to isolate the required compound in cases where the key esterification step is not regioselective and leads to an isomer mixture which has to be separated. In addition, the known method uses protective groups for the hydroxycinnamic reactants which can only be cleaved under drastic conditions (strong acid or strong base and heat), resulting in isomerization of the chlorogenic derivatives.